Adsorbent for hydrocarbon recovery

ABSTRACT

Disclosed in certain embodiments are sorbents for capturing heavy hydrocarbons via thermal swing adsorption processes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. non-provisional patentapplication Ser. No. 16/831,348, filed Mar. 26, 2020, which is acontinuation of U.S. non-provisional patent application Ser. No.15/737,192, filed Dec. 15, 2017, which is a national stage entry under35 U.S.C. § 371 of International Application Serial No.PCT/US2016/038038, filed on Jun. 17, 2016, which claims the benefit ofpriority of U.S. Provisional Patent Application No. 62/180,805, filedJun. 17, 2015, which are hereby incorporated by reference herein intheir entireties.

BACKGROUND

Hydrocarbons are commonly removed from natural gas to prevent thecondensation of liquids in pipeline transmission systems. Pipelinescommonly impose a dew point specification to prevent the condensation ofthe liquids, with hydrocarbon recovery units (HRUs) being utilized toremove heavy hydrocarbons in particular.

Silica gel sorbents have an affinity for heavy hydrocarbons, such as C6+components, and may be used in HRUs. In such systems, a fluid volume(e.g., natural gas) containing heavy hydrocarbons is passed through abed of silica gel to trap heavy hydrocarbons. Regeneration may beperformed by passing a pressurized and/or heated stream of natural gasfeed or product gas through the sorbent bed. After cooling, the heavyhydrocarbons contained in the effluent from the regeneration process canbe condensed as a liquid product and removed. In order to improve theadsorptive efficiency of such systems, there is a need to explore theuse of other sorbent materials that exhibit higher affinities for heavyhydrocarbons.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in which:

FIG. 1 depicts an illustrative sorbent bed in accordance with anembodiment of the disclosure; and

FIG. 2 illustrates a method for removing heavy hydrocarbons from a fluidvolume in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to a sorbent for improvedpurification of gas streams, and a system incorporating the sorbent andmethod of use thereof. More specifically, the present disclosure relatesto a sorbent used for the removal of heavy hydrocarbons (e.g., C5+ orC6+ components), water, acid gases, or other chemical species and therecovery of heavy hydrocarbons by use of an integrated process.

The adsorption process of the present disclosure, used to remove heavyhydrocarbons (e.g., C5+ or C6+ components) from fluid volumes (e.g., gasflows), may be accomplished by thermal swing adsorption. Thermal swingadsorption processes are generally known in the art for various types ofadsorptive separations. Generally, thermal swing adsorption processesutilize the process steps of adsorption at a low temperature,regeneration at an elevated temperature with a hot purge gas, and asubsequent cooling down to the adsorption temperature. Thermal swingadsorption processes are often used for drying gases and liquids and forpurification where trace impurities are to be removed. Thermal swingadsorption processes are often employed when the components to beadsorbed are strongly adsorbed on the adsorbent, and thus heat isrequired for regeneration.

In a thermal swing adsorption process, the regeneration temperature istypically higher than the adsorption temperature in order to effectdesorption of water and higher hydrocarbons. To illustrate, during thefirst adsorption step, which employs an adsorbent for the adsorption ofC5+ or C6+ components from a fluid volume (e.g., a raw natural gas feedstream), the temperature is maintained at less than 150° F. (66° C.) insome embodiments, and from about 60° F. (16° C.) to about 120° F. (49°C.) in other embodiments. In the desorption step of the presentdisclosure, the C6+ components adsorbed by the sorbent initially arereleased from the sorbent, thus regenerating the sorbent at temperaturesfrom about 300° F. (149° C.) to about 550° F. (288° C.) in someembodiments.

In this regeneration step, part of one of the fluid volumes (e.g., astream of natural gas), the product effluent from the adsorption unit,or a waste stream from a downstream process can be heated, and theheated stream is circulated through the adsorbent to desorb the adsorbedcomponents. In some embodiments, it advantageous to employ a hot purgestream comprising a heated raw natural gas stream for regeneration ofthe adsorbent.

In some embodiments, the pressures used during the adsorption andregeneration steps are generally elevated at typically 800 to 1200 psig.Typically, heavy hydrocarbon adsorption is carried out at pressuresclose to that of the feed stream and the regeneration steps may beconducted at about the adsorption pressure or at a reduced pressure.When a portion of an adsorption effluent stream is used as a purge gas,the regeneration may be advantageously conducted at about the adsorptionpressure, especially when the waste or purge stream is re-introducedinto the raw natural gas stream, for example.

FIG. 1 depicts an illustrate system 100 for removing heavy hydrocarbonsfrom a fluid volume. The system 100 includes a sorbent bed 110 that isadapted to receive a fluid volume in a thermal swing adsorptionconfiguration. The fluid volume flows into the sorbent bed 110 via inlet120, and passes out of the sorbent bed 110 via outlet 130.

In one aspect of the present disclosure, the system 100 includes asorbent bed comprising a sorbent adapted for adsorption of C5+ or C6+components from a fluid volume, wherein the sorbent has a compositioncomprising SiO₂ at a first weight percent greater than 99% and Al₂O₃ ata second weight percent less than 1%. In some embodiments, other sorbentcompositions may be used.

In some embodiments, the sorbent comprises a fluid-accessible surfacehaving a Brunauer-Emmett-Teller (BET) surface area greater than 600m²/g, greater than 700 m²/g, greater than 600 m²/g and less than 900m²/g, or greater than 700 m²/g and less than 800 m²/g. In suchembodiments, the sorbent is adapted to contact the fluid volume suchthat when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 10 ppm after thesorbent contacts the fluid volume. In some embodiments, the sorbentcomprises a fluid-accessible surface having a BET surface area greaterthan 725 m²/g and less than 775 m²/g.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 50 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 30 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 20 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 10 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 5 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 2 ppm after thesorbent contacts the fluid volume.

In some embodiments, the sorbent is adapted to contact the fluid volumesuch that when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 1 ppm after thesorbent contacts the fluid volume.

In some embodiments, the C6+ components comprise one or more of benzene,heptane, octane, nonane, toluene, or ethylbenzene. In some embodiments,the C6+ components consist essentially of benzene.

In some embodiments, a pore volume (e.g., Barrett-Joyner-Halenda (BJH)pore volume) of the sorbent is greater than 0.40 cm³/g, is greater than0.40 cm³/g and less than 0.50 cm³/g, or is greater than 0.425 cm³/g andless than 0.475 cm³/g. In some embodiments, a bulk density of thesorbent is less than 600 kg/m³. In some embodiments, the sorbent is in aform of sorbent pellets that form the sorbent bed (e.g., the sorbent bed110).

In some embodiments, the sorbent is amorphous. In some embodiments, arelative micropore surface area (RMA), which is the ratio of microporesurface area to BET surface area, of the sorbent is greater than 5%,greater than 10%, greater than 15%, greater than 20%, greater than 25%,or greater than 30%. As used herein, “micropore surface area” refers tototal surface area associated with pores below 200 Angstroms indiameter.

In some embodiments, a total pore volume for pores between 500 nm and20000 nm in diameter of the sorbent, as measured via mercuryporosimetry, is greater than 5 mm³/g, greater than 10 mm³/g, greaterthan 20 mm³/g, greater than 30 mm³/g, greater than 40 mm³/g, greaterthan 45 mm³/g, or greater than 50 mm³/g.

In some embodiments, a mass of the sorbent bed is greater than 22,500 kgand less than 27,500 kg. In such embodiments, a volume of the sorbentbed is greater than 40 m³ and less than 50 m³. In such embodiments, thesorbent is adapted to contact the fluid volume such that when the fluidvolume has an initial concentration of C6+ components that is greaterthan 150 ppm and less than 250 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 5 ppm after thesorbent contacts the fluid volume.

In some embodiments, a mass of the sorbent bed is greater than 19,000 kgand less than 23,000 kg. In such embodiments, a volume of the sorbentbed is greater than 30 m³ and less than 40 m³. In such embodiments, thesorbent is adapted to contact the fluid volume such that when the fluidvolume has an initial concentration of C6+ components that is greaterthan 150 ppm and less than 250 ppm, the fluid volume has a finalconcentration of C6+ components that is less than 5 ppm after thesorbent contacts the fluid volume.

In some embodiments, the mass of the sorbent bed is greater than 10,000kg and less than 15,000 kg. In such embodiments, the volume of thesorbent bed is greater than 6 m³ and less than 10 m³. In suchembodiments, the sorbent is adapted to contact the fluid volume suchthat when the fluid volume has an initial concentration of C6+components that is greater than 150 ppm and less than 250 ppm, the fluidvolume has a final concentration of C6+ components that is less than 35ppm after the sorbent contacts the fluid volume.

In some embodiments, the system is configured for thermalswing-adsorption.

In another aspect of the present disclosure, a sorbent bed (e.g.,sorbent bed 110) is adapted for removal of C6+ components from a fluidvolume such that the sorbent bed is capable of reducing a concentrationof the C6+ components in the fluid volume from greater than 150 ppm toless than 35 ppm, wherein a bulk density of the sorbent bed is less than600 kg/m³.

In another aspect of the present disclosure, a sorbent pellet has acomposition including SiO₂ at a first weight percent greater than 99%and Al₂O₃ at a second weight percent less than 1%. The sorbent pelletincludes a fluid-accessible surface having a BET surface area greaterthan 700 m²/g, wherein C6+ components are adsorbed to thefluid-accessible surface (e.g., after contacting the sorbent pellet witha fluid volume containing the C6+ components).

In another aspect of the present disclosure, a sorbent is adapted foradsorption of C6+ components, the sorbent having a characteristicselected from a group consisting of: a composition comprising SiO₂ at afirst weight percent greater than 99% and Al₂O₃ at a second weightpercent less than 1%; a fluid-accessible surface having a BET surfacearea greater than 700 m²/g; a bulk density of the sorbent that is lessthan 600 kg/m³; being adapted to adsorb C6+ components from a fluidvolume such that a C6+ component concentration of the fluid volume isreduced from greater than 150 ppm to less than 5 ppm; and combinationsthereof.

In another aspect of the present disclosure, a method of treating afluid volume comprises contacting the fluid volume with a sorbent,wherein: the fluid volume has an initial concentration of C6+ componentsprior to the contacting; and the fluid volume has a final concentrationof C6+ components after the contacting that is less than the initialconcentration of C6+ components. In some embodiments, the sorbentcomprises amorphous SiO₂ at a weight percent greater than 80%. In someembodiments, an RMA of the sorbent is greater than 10%. In someembodiments, a total pore volume for pores between 500 nm and 20000 nmin diameter is greater than 10 mm³/g.

In some embodiments, the sorbent comprises amorphous SiO₂ at a weightpercent greater than 85%, greater than 90%, greater than 95%, greaterthan 96%, greater than 97%, greater than 98%, or greater than 99%. Insome embodiments, the sorbent further comprises Al₂O₃ at a weightpercent of up to 20% (i.e., from greater than 0% to 20%), up to 15%, upto 10%, up to 9%, up to 8%, up to 7%, up to 6%, up to 5%, up to 4%, upto 3%, up to 2%, or up to 1%.

In some embodiments, the RMA of the sorbent is greater than 15%, greaterthan 20%, greater than 25%, or greater than 30%. In some embodiments, amicropore surface area of the sorbent is greater than 40 m²/g, greaterthan 50 m²/g, greater than 100 m²/g, greater than 150 m²/g, greater than200 m²/g, or greater than 230 m²/g. In some embodiments, the microporesurface area of the sorbent is from 40 m²/g to 300 m²/g, from 50 m²/g to300 m²/g, from 100 m²/g to 300 m²/g, from 150 m²/g to 300 m²/g, from 200m²/g to 300 m²/g, or from 230 m²/g to 300 m²/g.

In some embodiments, the total pore volume for pores between 500 nm and20000 nm in diameter is greater than 20 mm³/g, greater than 40 mm³/g,greater than 70 mm³/g, greater than 100 mm³/g, greater than 120 mm³/g,greater than 140 mm³/g, greater than 150 mm³/g, greater than 160 mm³/g,or greater than 170 mm³/g. In some embodiments, the total pore volumefor pores between 500 nm and 20000 nm in diameter is from 20 mm³/g to200 mm³/g, from 40 mm³/g to 200 mm³/g, from 70 mm³/g to 200 mm³/g, from100 mm³/g to 200 mm³/g, from 120 mm³/g to 200 mm³/g, from 140 mm³/g to200 mm³/g, from 150 mm³/g to 200 mm³/g, from 160 mm³/g to 200 mm³/g, orfrom 170 mm³/g to 200 mm³/g.

In some embodiments, the sorbent comprises a fluid-accessible surfacehaving a BET surface area greater than 400 m²/g, greater than 500 m²/g,greater than 600 m²/g, greater than 700 m²/g, greater than 800 m²/g, orgreater than 900 m²/g. In some embodiments, the BET surface area is from400 m²/g to 1000 m²/g, from 500 m²/g to 1000 m²/g, from 600 m²/g to 1000m²/g, from 700 m²/g to 1000 m²/g, from 800 m²/g to 1000 m²/g, or from900 m²/g to 1000 m²/g.

In some embodiments, an initial concentration of one or more of C5+ orC6+ components is greater than 150 ppm, greater than 250 ppm, greaterthan 500 ppm, greater than 1000 ppm, greater than 2000 ppm, or greaterthan 3000 ppm. In some embodiments, the initial concentration is from150 ppm to 4000 ppm, from 250 ppm to 4000 ppm, from 500 ppm to 4000 ppm,from 1000 ppm to 4000 ppm, from 2000 ppm to 4000 ppm, or from 3000 ppmto 4000 ppm. In some embodiments, the final concentration of one or moreof C5+ or C6+ components is less than 30 ppm, less than 20 ppm, lessthan 10 ppm, less than 5 ppm, less than 4 ppm, less than 3 ppm, lessthan 2 ppm, or less than 1 ppm.

In some embodiments, the C6+ components comprise one or more of benzene,heptane, octane, nonane, toluene, or ethylbenzene. In some embodiments,the sorbent is adapted to remove C5+ components from the fluid volume.In such embodiments, the C5+ components comprise neopentane.

In some embodiments, the sorbent is in a form of beads that form asorbent bed. In some embodiments, a size of the beads is from 2.4 mm to4 mm.

In another aspect of the present disclosure, a thermal swing adsorptionsystem comprises a sorbent bed comprising a sorbent. In someembodiments, the sorbent comprises amorphous SiO2 at a weight percentgreater than 80%. In some embodiments, an RMA of the sorbent is greaterthan 10%. In some embodiments, a total pore volume for pores between 500nm and 20000 nm in diameter is greater than 10 mm³/g.

FIG. 2 illustrates a method 200 for removing heavy hydrocarbons from afluid volume in accordance with an embodiment of the disclosure. Atblock 202, a sorbent bed including a plurality of sorbent particles isprovided. In some embodiments, the sorbent bed corresponds to thesorbent bed 110 described with respect to FIG. 1. At block 204, a fluidvolume is contacted with the sorbent particles. The fluid volume mayhave an initial concentration of C5+ or C6+ components (e.g., aconcentration of benzene and/or other components that is greater than150 ppm). At block 206, a final concentration of C5+ or C6+ componentsis measured for the fluid volume. In some embodiments, the contactingoccurs in a thermal swing-adsorption system.

ILLUSTRATIVE EXAMPLES

The following examples are set forth to assist in understanding thedisclosure and should not, of course, be construed as specificallylimiting the embodiments described and claimed herein. Such variationsof the disclosed embodiments, including the substitution of allequivalents now known or later developed, which would be within thepurview of those skilled in the art, and changes in formulation or minorchanges in experimental design, are to be considered to fall within thescope of the embodiments incorporated herein.

Example 1: Sorbent Bed Parameters

Table 1 below illustrates parameters of exemplary sorbent beds preparedusing different sorbents, in accordance with the embodiments describedherein. The exemplary sorbents used were Sorbead®H and Sorbead®LE32. Itis expected that heavy hydrocarbons other than benzene may be adsorbedin a similar manner under similar conditions.

TABLE 1 Sorbent bed parameters Sorbead ®H Sorbead ®LE32 Sorbead ®LE32Sorbead ®LE32 Kg adsorbed/bed 25,000 25,000 20807 12500 Volume (m³/bed)35.7 42.9 35.7 21.44 Final benzene 32 0 1 32 concentration (ppm) Density(kg/m³) 700 583 583 583

Example 2: Micropore Surface Area Measurements

Two sorbents, Sorbead®LE32 and Sorbead®H, were characterized vianitrogen porosimetry using a Micromeritics ASAP® 2000 porosimetrysystem. The resulting data was analyzed with Micromeritics ASAP® 2010software to determine micropore surface area and BET surface area, andis summarized in Table 2 below. Sorbead®LE32 was found to havesubstantially higher micropore surface area than Sorbead®H.

TABLE 2 RMA measurements Sorbead ®LE32 Sorbead ®H BET surface area(m²/g) 750 774 Micropore surface area (m²/g) 232 40 RMA (%) 31 5.2

Example 3: Pore Volume Measurements

Sorbead®LE32 and Sorbead®H were further characterized via mercuryporosimetry using a Thermo Scientific Pascal 140/240 porosimeter. Theresulting data was analyzed with “Pascal 140/240/440 v. 1.05” software,and is summarized in Table 3 below.

TABLE 3 Pore volume measurements Sorbead ®LE32 Sorbead ®H Pore volumebetween 500 nm 170 8 and 20000 nm (mm³/g)

The words “example” or “exemplary” are used herein to mean serving as anexample, instance, or illustration. Any aspect or design describedherein as “example” or “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects or designs. Rather, use ofthe words “example” or “exemplary” is intended to present concepts in aconcrete fashion. As used in this application, the term “or” is intendedto mean an inclusive “or” rather than an exclusive “or”. That is, unlessspecified otherwise, or clear from context, “X includes A or B” isintended to mean any of the natural inclusive permutations. That is, ifX includes A; X includes B; or X includes both A and B, then “X includesA or B” is satisfied under any of the foregoing instances. In addition,the articles “a” and “an” as used in this application and the appendedclaims should generally be construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform. Reference throughout this specification to “an embodiment”,“certain embodiments”, or “one embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. Thus, the appearancesof the phrase “an embodiment”, “certain embodiments”, or “oneembodiment” in various places throughout this specification are notnecessarily all referring to the same embodiment.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the disclosure should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A thermal swing adsorption system comprising abed of adsorbent particles, the adsorbent particles comprising amorphousSiO₂ particles, wherein a relative micropore surface area (RMA) of theamorphous SiO₂ particles is greater than 10%.
 2. The thermal swingadsorption system of claim 1, wherein a total pore volume of theamorphous SiO₂ particles for pores between 500 nm and 20000 nm indiameter is greater than 70 mm³/g.
 3. The thermal swing adsorptionsystem of claim 1, wherein a Brunauer-Emmett-Teller (BET) surface areaof the amorphous SiO₂ particles is greater than 500 m²/g.
 4. The thermalswing adsorption system of claim 1, wherein a bulk density of theamorphous SiO₂ particles is less than 600 kg/m³.
 5. The thermal swingadsorption system of claim 1, wherein a size of the amorphous SiO₂particles is from 2.4 mm to 4 mm.
 6. The thermal swing adsorption systemof claim 1, wherein the adsorbent particles further comprise Al₂O₃particles.
 7. The thermal swing adsorption system of claim 6, whereinthe amorphous SiO₂ particles are present at a weight % of greater than80%, and wherein the Al₂O₃ particles are present at a weight % of up to20%, wherein the weight % is calculated with respect to a total weightof the bed of adsorbent particles.
 8. A method of removing C5+ or C6+components from a fluid volume, the method comprising: contacting thefluid volume with a bed of adsorbent particles, the adsorbent particlescomprising amorphous SiO₂ particles, wherein a relative microporesurface area (RMA) of the amorphous SiO₂ particles is greater than 10%.9. The method of claim 8, wherein a total pore volume of the amorphousSiO₂ particles for pores between 500 nm and 20000 nm in diameter isgreater than 70 mm³/g.
 10. The method of claim 8, wherein aBrunauer-Emmett-Teller (BET) surface area of the amorphous SiO₂particles is greater than 500 m²/g.
 11. The method of claim 8, wherein abulk density of the amorphous SiO₂ particles is less than 600 kg/m³. 12.The method of claim 8, wherein a size of the amorphous SiO₂ particles isfrom 2.4 mm to 4 mm.
 13. The method of claim 8, wherein the adsorbentparticles further comprise Al₂O₃ particles.
 14. The method of claim 13,wherein the amorphous SiO₂ particles are present at a weight % ofgreater than 80%, and wherein the Al₂O₃ particles are present at aweight % of up to 20%, wherein the weight % is calculated with respectto a total weight of the bed of adsorbent particles.
 15. The method ofclaim 8, wherein the C6+ components comprise one or more of benzene,heptane, octane, nonane, toluene, or ethylbenzene.
 16. The method ofclaim 8, wherein the C5+ components comprise neopentane.
 17. The methodof claim 8, wherein an initial concentration of C5+ or C6+ components isgreater than 150 ppm, and wherein a final concentration of C5+ or C6+components is less than 30 ppm.
 18. A bed comprising of adsorbentparticles, the adsorbent particles comprising amorphous SiO₂ particles,wherein: a relative micropore surface area (RMA) of the amorphous SiO₂particles is greater than 10%, a total pore volume of the amorphous SiO₂particles for pores between 500 nm and 20000 nm in diameter is greaterthan 70 mm³/g, and a Brunauer-Emmett-Teller (BET) surface area of theamorphous SiO₂ particles is greater than 500 m²/g.
 19. The bed of claim18, wherein a bulk density of the amorphous SiO₂ particles is less than600 kg/m³.
 20. The bed of claim 18, wherein the bed is adapted for usein a thermal swing adsorption system.